A few days ago I encountered this racist COD:BO2 clan shouting some very ugly things ingame. I asked them to quit and I told them how pathetic they were. When I left the server both guys added me on steam and started to do what they do best apparently and started shouting more racists stuff and started to threathen me (LoL)

The 'Call Of Duty: Black Ops 2 - Security & Enforcement Policy says:

Offensive Behavior

Any user who is found to use aggressive, offensive, derogatory or racially charged language is subject to penalty.

First offense: User will be temporarily banned from playing the game online.

Second offense: User will be temporarily banned from playing the game online and will have voice chat privileges in the game revoked.

Extreme or repeat offenses: User will be permanently banned from playing the game online, will have their stats & emblems reset, and will be blocked permanently from appearing in leaderboards.